Foamed asphalt compositions, recycled asphalt composition including the same, asphalt pavement including the same, and methods of forming asphalt pavement using the same

ABSTRACT

Foamed asphalt compositions, recycled asphalt compositions, asphalt pavement, and methods of forming asphalt pavement using the foamed asphalt compositions are provided herein. An exemplary foamed asphalt composition is in a cellular matrix form and includes a base asphalt component and oxidized high density polyethylene. An exemplary asphalt pavement includes a recycled asphalt layer that includes the foamed asphalt composition and a recycled asphalt component. An exemplary method of forming asphalt pavement includes combining a base asphalt component and an oxidized high density polyethylene to form an asphalt mixture. The asphalt mixture is foamed using water and compressed air to form a foamed asphalt composition. The foamed asphalt composition and a recycled asphalt component are combined to form a recycled asphalt composition. A recycled asphalt layer is formed with the recycled asphalt composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/273,742, filed Dec. 31, 2015.

TECHNICAL FIELD

The technical field generally relates to foamed asphalt compositions,recycled asphalt composition including the foamed asphalt compositions,asphalt pavement including the foamed asphalt compositions, and methodsof forming asphalt pavement using the foamed asphalt compositions. Moreparticularly, the technical field relates to foamed asphalt compositionsthat provide asphalt pavement with excellent anti-deformationperformance and methods of forming asphalt pavement using the foamedasphalt compositions.

BACKGROUND

Asphalt compositions are commonly employed as paving materials for roadconstruction and maintenance. Typically, asphalt, often referred to as“asphalt binder” or “asphalt cement”, is mixed with aggregate to formmaterial used in asphalt paving. Processing and use of this material bypaving crews yields asphalt pavement. Asphalt pavement conventionallyincludes a layer of aggregate held within a continuous phase of theasphalt by adherence of the asphalt to the aggregate.

Asphalt pavement formed in accordance with road maintenance orreplacement often includes a recycled asphalt layer as a base layer thatis disposed underneath a conventional hot mix asphalt (HMA) layer. Coldrecycling techniques, including cold-in-place and cold-in-planttechniques, are commonly employed to form the recycled asphalt layerwhereby recycled asphalt pavement (RAP) is pulverized and reconstitutedwith a foamed asphalt composition, amongst other optional componentssuch as active filler (e.g., cement, lime, and the like) and freshaggregate. The foamed asphalt composition enables generally homogenousmixing and binding of the RAP and other optional components at ambientprocessing temperatures of from about 10° C. to about 50° C. Processingat such relatively low temperatures, hereinafter deemed“low-temperature” or “cold” processing, enables energy consumption andhazard emissions to be minimized and also enables more RAP to be usedinstead of fresh aggregate while still achieving target physicalperformance.

Presently, foamed asphalt compositions that are employed to form therecycled asphalt layer consist of water and asphalt. It has generallybeen accepted that no further modifiers, e.g., elastomeric additives,can be included in the foamed asphalt compositions because suchadditives inhibit effective foaming. However, recycled asphalt layersformed using conventional foamed asphalt compositions generally exhibitpoor permanent deformation resistance, resulting in rut formation overtime in the asphalt pavement especially for asphalt pavement that issubject to heavy traffic loads and channelized traffic. To account forrutting tendencies attributable to the recycled asphalt layers,thickness of the HMA layer is generally adjusted to meet anti-ruttingperformance targets with HMA layer thicknesses in excess of 8 cm typicalfor purposes of achieving anti-rutting performance of at least 5000cycles/mm as measured in accordance with T0719-2011 of the IndustryStandard JTG E20-2011 Specification and Test Methods of Bitumen andBituminous Mixture for Highway Engineering, China.

Accordingly, it is desirable to provide foamed asphalt compositions,recycled asphalt compositions, asphalt pavement, and methods of formingasphalt pavement using the foamed asphalt compositions with maximizedanti-rutting performance. Furthermore, other desirable features andcharacteristics will become apparent from the subsequent detaileddescription and the appended claims, taken in conjunction with theaccompanying drawings and this background.

BRIEF SUMMARY

Foamed asphalt compositions, recycled asphalt compositions, asphaltpavement, and methods of forming asphalt pavement using the foamedasphalt compositions are provided herein. In an embodiment, a foamedasphalt composition includes a base asphalt component and oxidized highdensity polyethylene. The foamed asphalt composition is in a cellularmatrix form.

In another embodiment, an asphalt pavement includes a recycled asphaltlayer. The recycled asphalt layer includes a foamed asphalt compositionand a recycled asphalt component. The foamed asphalt compositionincludes a base asphalt component and oxidized high densitypolyethylene.

In another embodiment, a method of forming asphalt pavement includescombining a base asphalt component and an oxidized high densitypolyethylene to form an asphalt mixture. The asphalt mixture, water, andcompressed air are foamed to form a foamed asphalt composition. Thefoamed asphalt composition and a recycled asphalt component are combinedto form a recycled asphalt composition. A recycled asphalt layer isformed with the recycled asphalt composition.

BRIEF DESCRIPTION OF THE DRAWINGS

The various embodiments will hereinafter be described in conjunctionwith the following drawing figures, wherein like numerals denote likeelements, and wherein:

FIG. 1 is a schematic drawing of asphalt foaming equipment and a processof forming a foamed asphalt composition in accordance with anembodiment;

FIG. 2 is a schematic cross-sectional side view of asphalt pavement inaccordance with an embodiment; and

FIG. 3 is a schematic drawing of repaving equipment and process offorming asphalt pavement employing a cold-in-place technique inaccordance with an embodiment.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and isnot intended to limit the foamed asphalt compositions, asphalt pavementincluding the foamed asphalt compositions, and methods of formingasphalt pavement using the foamed asphalt compositions. Furthermore,there is no intention to be bound by any theory presented in thepreceding background or the following detailed description.

Foamed asphalt compositions, recycled asphalt compositions, asphaltpavement, and methods of forming asphalt pavement using the foamedasphalt compositions are provided herein that provide maximizedanti-rutting performance. In particular, the foamed asphalt compositionsinclude oxidized high density polyethylene (OxHDPE), in addition to abase asphalt component, with the OxHDPE providing maximized anti-ruttingperformance to recycled asphalt layers that are formed using the foamedasphalt compositions and recycled asphalt pavement (RAP). Foamed asphaltcompositions, as referred to herein, are in cellular matrix form and maybe formed by foaming an asphalt mixture of the base asphalt componentand OxHDPE using compressed air, water, and a foam nozzle. RAP, asreferred to herein, is pulverized asphalt pavement obtained from anexisting structure (e.g., an existing road, parking lot, etc.) that isbeing repaired, replaced, or removed. When used in asphalt pavement thatincludes a hot mix asphalt (HMA) layer overlying the recycled asphaltlayer, the maximized anti-rutting performance of the recycled asphaltlayers described herein enables target anti-rutting performance to beachieved with thinner HMA layers than have conventionally been necessaryto meet the target anti-rutting performance for the asphalt pavement.Further, in embodiments, an additional polyethylene different from theoxidized high density polyethylene and chosen from oxidized low densitypolyethylene (OxLDPE), non-oxidized polyethylene homopolymer, or acombination thereof is also included in the foamed asphalt compositionsin addition to the OxHDPE. The additional polyethylene unexpectedlyprovides the recycled asphalt layers with maximized indirect tensilestrength and minimizes viscosity of the foamed asphalt composition at160° C. to enhance surface coating of the RAP, thereby further enhancingthe recycled asphalt layers as compared to conventional recycled asphaltlayers.

As alluded to above, the foamed asphalt compositions include the baseasphalt component and OxHDPE. The base asphalt component, as referred toherein, is neat asphalt that is free of polymers. The neat asphalt isoften a byproduct of petroleum refining or post refining operations andincludes air-blown asphalt, blended asphalt, cracked or residualasphalt, petroleum asphalt, propane asphalt, straight-run asphalt,thermal asphalt, and the like. In embodiments, the base asphaltcomponent is present in the foamed asphalt composition in an amount offrom about 88 to about 98 weight %, such as from about 92 to about 98weight %, based upon a total weight of the foamed asphalt composition ona dry basis.

The OxHDPE is provided in the foamed asphalt composition to providemaximized anti-rutting performance to the recycled asphalt layer formedusing the foamed asphalt composition. In embodiments, the OxHDPE, asreferred to herein, is oxidized polyethylene having a density of fromabout 0.97 to about 1.01 g/cm³. In embodiments, the OxHDPE has a numberaverage molecular weight (M_(n)) of from about 1000 to about 30,000Daltons, such as from about 1000 to about 10,000 Daltons. Further, inembodiments, the OxHDPE may have a degree of oxidation, e.g., carboxylgroup content as indicated by acid number, of from about 5 to about 50(e.g. acid value of about 5 to about 50 mg KOH/g), and more preferablyof from about 15 to about 40 (e.g. acid value of about 15 to about 40 mgKOH/g). Acid number may be determined by titrating a solution of theOxHDPE with a 0.1 N alcoholic potassium hydroxide (KOH) solution to avisual “pink” end point using phenolphthalein as an indicator inaccordance with conventional techniques. In embodiments, the OxHDPE hasa viscosity of from about 100 to about 20000 cP at 150° C. as measuredin accordance with ASTM D4402. Examples of suitable OxHDPE include, butare not limited to, Honeywell Titan® 7456, Honeywell Titan® 7686,Honeywell Titan® 7376, Honeywell Titan® 7608, Honeywell Titan® 7709, andHoneywell Titan® 7410 oxidized high-density polyethylene homopolymers,manufactured by Honeywell International Inc., which is headquartered inMorristown, N.J.

In embodiments, the foamed asphalt composition further includes anadditional polyethylene that is different from the oxidized high densitypolyethylene. The additional polyethylene may be provided in the foamedasphalt composition to adjust physical properties other thananti-rutting of recycled asphalt layers that include the foamed asphaltcomposition. More specifically, it was found that by including OxHDPE inthe foamed asphalt composition, indirect tensile strength (ITS) of therecycled asphalt layers formed using the foamed asphalt composition isreduced as compared to conventional recycled asphalt layers formed usingconventional foamed asphalt compositions. However, it was alsounexpectedly found that by including the additional polyethylene, ITSperformance of at least equal to that of conventional recycled asphaltlayers formed using conventional foamed asphalt compositions can beachieved, often with increased ITS performance observed. It is believedthat ITS correlates to potential for cracking and field pavementmoisture damage.

The additional polyethylene may be chosen from non-oxidized polyethylenehomopolymer, oxidized low density polyethylene (OxLDPE), or acombination thereof. In embodiments, the additional polyethylene isOxLDPE and may have a density of from about 0.84 to about 0.95 g/cm³. Inembodiments, the OxLDPE has a number average molecular weight (M_(n)) offrom about 1000 to about 10000 Daltons, such as from about 1000 to about5000 Daltons. Further, in embodiments, the OxLDPE may have a degree ofoxidation, e.g., carboxyl group content as indicated by acid number, offrom about 5 to about 30 (e.g. acid value of about 5 to about 30 mgKOH/g), and more preferably of from about 10 to about 20 (e.g. acidvalue of about 10 to about 20 mg KOH/g). Acid number may be determinedby titrating a solution of the OxLDPE with a 0.1 N alcoholic potassiumhydroxide (KOH) solution to a visual “pink” end point usingphenolphthalein as an indicator in accordance with conventionaltechniques. In other embodiments, the additional polyethylene is thenon-oxidized polyethylene homopolymer and may have a density of fromabout 0.87 to about 0.98 g/cm³ and a viscosity of from about 10 to about7000 cP at 140° C. as measured in accordance with ASTM D4402. Specificexamples of suitable additional polyethylenes include Honeywell Titan®7183, Honeywell Titan® 7595, and Honeywell Titan® 7984 oxidized lowdensity polyethylene and Honeywell Titan® 7287, Honeywell Titan® 7205,and Honeywell Titan® 7467 non-oxidized polyethylene homopolymer.

In embodiments, a combined amount of all polymeric species present inthe foamed asphalt composition (i.e., a total amount of all OxHDPE andadditional polyethylene) is from about 2 to about 10.5 weight %, such asfrom about 2 to about 8 weight %, based upon a total weight of thefoamed asphalt composition on a dry basis. In embodiments, a weightratio of OxHDPE to additional polyethylene in the foamed asphaltcomposition is from about 1:3 to about 2:1, such as from about 1:2 toabout 2:1 or from about 1:3 to about 1:1.

In an embodiment and referring to FIG. 1, using conventional asphaltfoaming equipment 10 including a foam nozzle 12, the foamed asphaltcomposition 14 is produced by introducing an asphalt composition 16including the base asphalt component, the OxHDPE, and optionally theadditional polyethylene to the foam nozzle 12. In the embodiment shown,the OxHDPE and optional additional polyethylene are incorporated withthe base asphalt component 16 to form the asphalt mixture 16. Theasphalt mixture 16 is foamed using water 18 and compressed air 20 toform the foamed asphalt composition 14 in cellular matrix form. Inembodiments, the asphalt composition 16 is heated to a temperature offrom about 150° C. to about 170° C. and is pumped under pressure, e.g.,at a pressure of about 0.3 MPa, to a mixing zone where the asphaltcomposition 16 is mixed with water 18 and compressed air 20. Inembodiments, the water 18 is mixed with the asphalt mixture 16 in anamount of from about 2 to about 5 weight %, such as from about 2 toabout 4 weight %, based upon a combined total weight of the water andall components present in the asphalt mixture 16. In embodiments, thetemperature of the asphalt mixture 16 during foaming (i.e., at an outletfrom the foaming nozzle) is from about 140 to about 180° C., such asfrom about 155 to about 165° C.

In embodiments, the asphalt mixture 16 includes the additionalpolyethylene and the asphalt mixture 16 has a viscosity of at leastabout 30,000 Pa·s at a temperature of 60° C. and a viscosity of lessthan about 150 cP at a temperature of 160° C., wherein viscosity isdetermined in accordance with ASTM D4402. It has been found that thepresence of the additional polyethylene may decrease the viscosity ofthe asphalt mixture 16 at 160° C. as compared to embodiments in whichonly the OxHDPE is present to the exclusion of the additionalpolyethylene. The temperature of 160° C. is a typical temperature of thebase asphalt component 16 during foaming, and without being bound by anyparticular theory, it is believed that the decreased viscosity of theasphalt mixture 16 at that temperature results in more effective foamingand better coating of RAP during formation of the recycled asphalt layer24, thereby leading to maximized ITS performance Additionally, theOxHDPE maximizes viscosity of the asphalt mixture 16 at a temperature ofabout 60° C. and, without being bound by any particular theory, it isbelieved that maximized viscosity of the asphalt mixture 16 at 60° C.leads to maximized anti-rutting performance. As such, it is believedthat the presence of both the OxHDPE and the additional polyethylenemaximizes anti-rutting and ITS performance of recycled asphalt layersand, in turn, asphalt pavement 22 including the recycled asphalt layers.

In embodiments and referring to FIG. 2 with continued reference to FIG.1, the foamed asphalt composition 14 is employed in recycled asphaltcompositions, which is in turn employed in asphalt pavement 22 thatincludes a recycled asphalt layer 24 and a hot mix asphalt (HMA) layer26 disposed over the recycled asphalt layer 24. In embodiments, therecycled asphalt composition and the recycled asphalt layer 24 includethe foamed asphalt composition 14 and a recycled asphalt component, suchas RAP. Additional components may also be included in the recycledasphalt composition such as, but not limited to, active filler and freshaggregate. Suitable active fillers include, but are not limited to,cement, lime, and the like. “Aggregate” is a collective term for mineralmaterials, such as, for example, sand, gravel, or crushed stone that arecombined with the asphalt binder to form the asphalt paving material.The aggregate may comprise natural aggregate, manufactured aggregate, ora combination thereof. Natural aggregate is typically extracted rockfrom an open excavation (e.g. a quarry) that is reduced to usable sizesby mechanical crushing. Manufactured aggregate is typically a byproductof other manufacturing processes such as slag from metallurgicalprocessing (e.g. steel, tin, and copper production). Manufacturedaggregate also includes specialty materials that are produced to have aparticular physical characteristic not found in natural rock, such as,for example, low density.

In embodiments, the recycled asphalt layer 24 is formed from therecycled asphalt composition that includes the foamed asphaltcomposition in an amount of from about 2 to about 5 weight %, such asfrom about 2 to about 4 weight %, based on the total weight of therecycled asphalt composition. The recycled asphalt component may bepresent in the recycled asphalt composition in an amount of from about50 to about 98 weight %, such as from about 70 to about 98 weight %,based on the total weight of the recycled asphalt composition. Theoptional additional components may be present in the recycled asphaltcomposition in an amount of from about 0 to about 50 weight %, such asfrom about 0 to about 30 weight %, based on the total weight of therecycled asphalt composition.

The HMA layer 26 includes a conventional asphalt mix and is formed inaccordance with conventional techniques. For example, the conventionalHMA may have 93-96% aggregates and 4%-7% asphalt or the asphalt mixture16 described above. The mixing temperature may be from about 140 toabout 190° C.

As alluded to above, the foamed asphalt composition as described hereinprovides the recycled asphalt layer 24 with maximized anti-ruttingperformance and, in embodiments, also provides maximized ITSperformance. For example, in embodiments, the recycled asphalt layer 24has anti-rutting performance of at least 5000 cycles/mm at a temperatureof 60° C. Anti-rutting performance may be measured in accordance withT0719-2011 of the Industry Standard JTG E20-2011 Specification and TestMethods of Bitumen and Bituminous Mixture for Highway Engineering, Chinausing a Wheel Tracking Machine having a wheel with a width of 5centimeters. A pressure of 0.7 MPa is applied to the recycled asphaltlayer 24 specimen having a length of 30 cm and a thickness of 5 cm. Thewheel of the Wheel Tracking Machine moves at a speed of 42 passing perminute. The test is carried out for 1 hour and the rutting is observedat a predetermined interval of cycles. Anti-rutting performance ismeasured in average number of cycles required to create 1 mm depth ofrutting in the last 15 minutes. In embodiments, the recycled asphaltlayer 24 has an ITS of at least 0.45 MPa as measured in accordance withASTM D6931-12.

As alluded to above, given the maximized anti-rutting and, optionally,maximized ITS performance of the recycled asphalt layer 24, it isbelieved that a thinner HMA layer may be employed while still achievingdesired anti-rutting performance and, optionally, desired ITSperformance of the asphalt pavement. More specifically, in embodiments,the HMA layer 26 has a thickness 28 of from 4 to less than 8 cm, therecycled asphalt layer 24 has a thickness 30 of from about 10 to about18 cm, and the recycled asphalt layer 24 has anti-rutting performance ofat least 5000 cycles/mm as measured in accordance with testing procedureas described above. In further embodiments, the additional polyethyleneis also present and recycled asphalt layer 24 has an ITS of at least0.45 MPa as measured in accordance with ASTM D6931-12.

In embodiments and referring to FIG. 3 with continued reference to FIGS.1 and 2, the asphalt pavement 22 is formed using conventional repavingequipment 36 by combining the base asphalt component and the oxidizedhigh density polyethylene to form the asphalt mixture 16 and foaming theasphalt mixture 16 using water 18 and compressed air 20 to form thefoamed asphalt composition 14 as shown in FIG. 1 and as described abovein regards the exemplary method of producing the foamed asphaltcomposition 14. Referring to FIG. 3, the foamed asphalt composition 14and the recycled asphalt component 32 are combined to form the recycledasphalt composition 34. The recycled asphalt layer 24 is formed with therecycled asphalt composition 34. In embodiments, the steps of combiningto form the asphalt mixture 16, foaming, combining to form the recycledasphalt composition 34, and forming the recycled asphalt layer 24 areconducted at ambient temperatures of from about 10° C. to about 50° C.,although it is to be appreciated that the internal temperatures of theindividual components and compositions may be significantly greater than50° C.°. In embodiments and although not shown in FIG. 3, the HMA layer26 is formed over the recycled asphalt layer 24 through conventionaltechniques.

Example A

Foamed asphalt compositions (FACs) are prepared by heating a baseasphalt component to a temperature of about 160° C. (for purposes ofComp. FAC A in TABLE AI), followed by the addition of OxHDPE to form anasphalt mixture (for purposes of FAC A in TABLE AI). The respective baseasphalt component and the asphalt mixture were provided to a foamedasphalt machine followed by foaming using water and compressed air toform the FACs. TABLE AI provides a listing of the components included inthe FACs with all amounts in weight % based upon total weight of theFACs.

TABLE AI Base Asphalt Component OxHDPE 1 Water Comp. FAC A 97.56 0 2.44FAC A 92.17 5.53 2.30

Base asphalt component is ZH70#, local Chinese base asphalt, with apenetration at 25° C. of from 60 to 80 (0.1 mm).

OxHDPE 1 is Honeywell Titan® 7686 having a density of 0.99 g/cm³.

Viscosities of the asphalt mixtures (AM) including the components of therespective FACs listed in TABLE AI, inclusive of water, are set forth inTABLE All and were measured at 60° C. and 160° C. in accordance withASTM D4402.

TABLE AII Visc. @ Visc. @ 60° C. (Pa · s) 160° C. (cP) Comp. AM A 198135 AM A >50000 175

Recycled asphalt compositions were prepared using the foamed asphaltcompositions shown in TABLE AI and recycled asphalt layers were formedfrom the recycled asphalt compositions. To prepare the recycled asphaltcompositions, the asphalt mixtures (AM) were pumped to the foamedasphalt machine. Foamed asphalt compositions were formed and mixed withadditional components as set forth in TABLE AIII below, with all amountsin weight % based upon total weight of the resulting recycled asphaltcompositions.

TABLE AIII Comp. Ex. Ex. Comp. FAC .A 2.50 0.00 FAC.A 0.00 2.50 RAP76.56 76.56 Active filler 1.91 1.91 Coarse fresh aggregate 10.53 10.53Fine fresh aggregate 8.61 8.61Active fresh filler is cement.Coarse Fresh Aggregate is aggregate with a normal size of from 10 mm-30mmFine Fresh Aggregate is aggregate with a normal size of from 0 mm-5 mm

Physical properties of recycled asphalt layers formed from the recycledasphalt compositions were tested as shown in TABLE AIV. Anti-ruttingperformance may be measured in accordance with conventional testingusing a Wheel Tracking Machine having a wheel with a width of 5centimeters. A pressure of 0.7 MPa is applied to the recycled asphaltlayer 24 specimen having a length of 30 cm and a thickness of 5 cm. Thewheel of the Wheel Tracking Machine moves at a speed of 42 passing perminute. The test is carried out for 1 hour and the rutting is observedat a pre-determined interval of cycles. Anti-rutting performance ismeasured in number of cycles required to create 1 mm depth of rutting.ITS was measured in accordance with ASTM D6931-12. ITS ratio (ITSR) wasmeasured as a ratio of wet ITS to dry ITS, with ITS measured inaccordance with ASTM D6931-12. The wet ITS was measured by soaking thespecimen in a 25° C. water bath for 24 hours.

TABLE AIV Comp. Ex. A Ex. A Anti-Rutting, cycles/mm 4507 9267 ITS, MPa0.42 0.37 ITSR, % 77 75

Example B

In this Example, the FACs were prepared in the same manner as describedabove in EXAMPLE A, but with alternatives to the OxHDPE as well ascombinations of OxHDPE and some additional polymers used. TABLE BIprovides a listing of the components included in the FACs with allamounts in weight % based upon total weight of the FACs.

TABLE BI Base Asphalt Homo. OxHDPE OxHDPE Component OxFT OxLDPE PE 1 2Water Comp. FAC B1 97.56 0 0 0 0 0 2.44 Comp. FAC B2 92.17 5.53 0 0 0 02.30 Comp. FAC B3 92.17 0 5.53 0 0 0 2.30 Comp. FAC B4 92.17 0 0 5.53 00 2.30 FAC B1 92.17 0 0 0 5.53 0 2.30 FAC B2 92.17 0 0 0 0 5.53 2.30 FACB3 92.17 0 2.76 0 2.76 0 2.30 FAC B4 92.17 0 4.15 0 1.38 0 2.30 FAC B592.17 0 0 2.76 2.76 0 2.30 FAC B6 92.17 4.15 0 0 1.38 0 2.30OxFT is oxidized Frisch-Tropsch wax.OxHDPE 2 is Honeywell Titan® 7456 having a density of 0.98 g/cm³.OxLDPE is Honeywell Titan® 7183 oxidized LDPE having a density of 0.93g/cm³.Homo. PE is Honeywell Titan® 7287 non-oxidized homopolymer polyethylenehaving a density of 0.91 g/cm³.

Viscosities of the asphalt mixtures (AM) including the components of therespective FACs listed in TABLE AI, inclusive of water, are set forth inTABLE BII and were measured at 60° C. and 160° C. in accordance withASTM D4402.

TABLE BII Visc. @ 60° C. Visc. @ 160° C. (Pa · s) (cP) Comp. AM B1 198135 Comp. AM B2 136 101 Comp. AM B3 515 126.7 Comp. AM B4 883 125 AMB1 >50000 175 AM B2 >50000 192 AM B3 >50000 140.8 AM B4 31000 135 AM B542800 146 AM B6 41080 115.8

Recycled asphalt compositions were prepared using the foamed asphaltcompositions shown in TABLE BI and recycled asphalt layers were formedfrom the recycled asphalt compositions in the same manner as describedabove in EXAMPLE A. To form the recycled asphalt compositions, foamedasphalt compositions were formed and mixed with additional components asset forth in TABLE BIII below, with all amounts in weight % based upontotal weight of the resulting recycled asphalt compositions.

TABLE BIII Comp. Ex. B1 Ex. B1 Ex. B2 Ex. B3 Ex. B4 Ex. B5 Comp. FAC B12.5 0 0 0 0 0 FAC B1 0 2.5 0 0 0 0 FAC B3 0 0 2.5 0 0 0 FAC B4 0 0 0 2.50 0 FAC B5 0 0 0 0 2.5 0 FAC B6 0 0 0 0 0 2.5 RAP 76.56 76.56 76.5676.56 76.56 76.56 Active Filler 1.91 1.91 1.91 1.91 1.91 1.91 CoarseFresh 10.53 10.53 10.53 10.53 10.53 10.53 Aggregate Fine Fresh 8.61 8.618.61 8.61 8.61 8.61 Aggregate

Physical properties of recycled asphalt layers formed from the recycledasphalt compositions were tested as shown in TABLE BIV. Anti-ruttingperformance, ITS, and ITSR was measured as set forth above in thecontext of Example A.

TABLE BIV Comp. Ex. B1 Ex. B1 Ex. B2 Ex. B3 Ex. B4 Ex. B5 Anti-Rutting,3044 6019 6966 3929 3234 3619 cycles/mm ITS, MPa 0.48 0.41 0.51 0.560.54 0.54 ITSR, % 77.5 89 88.5 75 77.8 75

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or exemplary embodiments are only examples, and arenot intended to limit the scope, applicability, or configuration in anyway. Rather, the foregoing detailed description will provide thoseskilled in the art with a convenient road map for implementing anexemplary embodiment. It being understood that various changes may bemade in the function and arrangement of elements described in anexemplary embodiment without departing from the scope as set forth inthe appended claims.

What is claimed is:
 1. A foamed asphalt composition comprising: a base asphalt component; and oxidized high density polyethylene; wherein the foamed asphalt composition is in a cellular matrix form.
 2. The foamed asphalt composition of claim 1, wherein the oxidized high density polyethylene has a density of from about 0.97 to about 1.01 g/cm³.
 3. The foamed asphalt composition of claim 1, further comprising an additional polyethylene different from the oxidized high density polyethylene and chosen from non-oxidized polyethylene homopolymer, oxidized low density polyethylene, or a combination thereof.
 4. The foamed asphalt composition of claim 3, wherein the additional polyethylene is oxidized low density polyethylene having a density of from about 0.84 to about 0.95 g/cm³.
 5. The foamed asphalt composition of claim 3, wherein the additional polyethylene is non-oxidized polyethylene homopolymer having a density of from about 0.87 to about 0.98 g/cm³.
 6. The foamed asphalt composition of claim 3, where a combined amount of all polymeric species present in the foamed asphalt composition is from about 2 to about 10.5 weight % based upon a total weight of the foamed asphalt composition on a dry basis.
 7. The foamed asphalt composition of claim 3, wherein the oxidized high density polyethylene and the additional polyethylene are present in the foamed asphalt composition in a weight ratio of from about 1:2 to about 2:1.
 8. The foamed asphalt composition of claim 1, produced by: introducing the base asphalt component, the oxidized high density polyethylene, optionally an additional polyethylene different from the oxidized high density polyethylene, and water to a foam nozzle; and foaming a mixture of the base asphalt component, the oxidized high density polyethylene, by using water and compressed air to form the foamed asphalt composition in the cellular matrix form.
 9. The foamed asphalt composition of claim 8, wherein water is present in the mixture in an amount of from about 2 to about 5 weight % based upon a total weight of all components present in the mixture.
 10. The foamed asphalt composition of claim 8, wherein the mixture comprises the additional polyethylene and wherein the mixture has a viscosity of at least about 30,000 Pa·s at a temperature of 60° C. and a viscosity of less than about 150 cP at a temperature of 160° C., wherein viscosity is determined in accordance with ASTM D4402.
 11. A recycled asphalt composition comprising: the foamed asphalt composition of claim 1; and a recycled asphalt component.
 12. An asphalt pavement comprising: a recycled asphalt layer comprising: a foamed asphalt composition comprising: a base asphalt component; and oxidized high density polyethylene; and a recycled asphalt component.
 13. The asphalt pavement of claim 12, wherein the foamed asphalt composition further comprises an additional polyethylene different from the oxidized high density polyethylene and chosen from non-oxidized polyethylene homopolymer, oxidized low density polyethylene, or a combination thereof.
 14. The asphalt pavement of claim 13, wherein the recycled asphalt layer has an indirect tensile strength of at least 0.45 Mpa as measured in accordance with ASTM D6391-12.
 15. The asphalt pavement of claim 12, further comprising a hot mix asphalt layer disposed over the recycled asphalt layer.
 16. The asphalt pavement of claim 15, wherein the hot mix asphalt layer has a thickness of from 4 to less than 8 cm, the recycled asphalt layer has a thickness of from about 10 to about 18 cm, and the recycled asphalt layer has anti-rutting performance of at least 5000 cycles/mm at 60° C. in accordance with T0719-2011 of the Industry Standard JTG E20-2011 Specification and Test Methods of Bitumen and Bituminous Mixture for Highway Engineering, China.
 17. A method of forming asphalt pavement, said method comprising the steps of: combining a base asphalt component and an oxidized high density polyethylene to form an asphalt mixture; foaming the asphalt mixture using water and compressed air to form a foamed asphalt composition; combining the foamed asphalt composition and a recycled asphalt component to form a recycled asphalt composition; and forming a recycled asphalt layer with the recycled asphalt composition.
 18. The method of claim 17, wherein the steps of combining to form the asphalt mixture, foaming, combining to form the recycled asphalt composition, and forming the recycled asphalt layer are conducted at ambient temperatures of no greater than about 50° C.
 19. The method of claim 17, wherein the foamed asphalt composition further comprises an additional polyethylene different from the oxidized high density polyethylene and chosen from non-oxidized polyethylene homopolymer, oxidized low density polyethylene, or a combination thereof.
 20. The method of claim 17, further comprising forming a hot mix asphalt layer over the recycled asphalt layer. 